Balancing machine with electrical indicating device



Fig. 7

, fig -3 INVENTOR W. PISCH EL Filed Sept. 11, 195] BALANCING MACHINEWITH ELECTRICAL INDICATING DEVICE Fig. z

May 18, 1954 type.

the unbalance from the relative phase of the two Patented May 18, 1 954UNITED STATES PATENT OFFICE BALANCING MACHINE WITH ELECTRICAL INDICATINGDEVICE Werner Pischel, Dusseldorf, Germany Application September 11,1951, Serial No. 246,083

3 Claims.

of converting the force of unbalance or oscillation, produced by theunbalance of the body to be balanced, into corresponding alternatingcurrent. Various types of electro-mechanical transformers can beemployed for such purpose. The

testing currents thus produced have a frequency *which corresponds tothe rotary speed of the body to be balanced, and an amplitude whichdepends on the magnitude of the unbalance.

It is also known that for the purpose of ascertaining the location ofthe unbalance an auxiliary alternating current of equal frequency isgenerated which together with the testing ourrent is delivered to anindicating device preferably oi dynamornetric or correspondingly actingThus it is possible to deduce thelocation of alternating currents.Namely, when the phases of the two alternating currents are displacedfrom one another by 90 or 270, the indicating instrument will read zero,whereas at a phase displacement of 0 or 180 there will be a maximumplaced, in known manner, so long until the instrument indicates zero.The angle by which the phase must be displaced thereby gives thelocation of the unbalance. If, starting from the phase relationjustobtained, the phase is then displaced by 99, a maximum deflection of thepointer will be obtained on the scale of the indicating instrument, fromwhich the magnitude of the unbalance can be derived.

It is the primary object of the present invention to automatize thismeasuring .method just described which is generally known and by way ofexample also used in United States Patent 1 No. 2,362,842 so as toeliminate setting errors, further to shorten the balancing operation andto make it foolproof. This is a major feature of advantage ofconsiderable importance particularly in large-lot balancing ofmass-produced I parts.

To this end the invention consists therein that the phase is continuallychanged by means of an auxiliary drive of a phase advancer and, on zeroreading on the scale of the indicating instrument,

trio motor 3 by means of a coupling 2.

2 the auxiliary drive is cut-out by means of an automatic switchgear andthen another switchgear is cutdn which effects a 90 phase displacement.

In doing so it is the purpose to employ a D. C. measuringinstrument asindicating instrument, which cooperates in known manner with a modulatorwhich is fed by the two alternating currents, and which is preferably ofsuch a type having the zero position in the middle of its scale.Further, the indicating instrument is preferably provided with aphoto-electric control device which, in the zero position of thepointer, aetuates a relay which in turn actuates the switchgear. Anadditional purpose is for the switchgear to operate an electro-magneticclutch between the auxiliary drive andthe phase advancer, so as to shutdown the phase advancer at the moment at which the pointer min the zeroposition. Instead of using an ohmicresistance to obtain the 90 phasedisplacement required for measuring the magnitude of the unbalance, thiscan be eiiected in a most simple manner by the switchgear connecting asuitable condenser to the alternating current circuit of the phaseadvancer. At the same time the switchgear maycause a signal light tocome on for the purpose of indicating the completion of the balancingoperation.

One form of construction of the invention is illustrated, by way ofexample, in the annexed drawings, in which- Fig. 1 is a diagrammatic andperspective view illustrating the balancing machine and automaticindicating device provided by the invention.

Fig. 2 is a wiring diagram of the modulator which in Fig.1 is shown as aclosed box.

Fig. 3 is a wiring diagram of the rotary-field systems above describedfor generating the auxiliary alternating current and causing its phasedisplacement.

In the drawings, the numeral i represents the body to be balanced whichis supported on two V-shaped bearings 4, 4 and driven from an elec- Theforce of unbalance which is formed on rotating of the body I. is, bymeans 01 electro-mechanical transformers 5, .5, for instance,piezo-electric quartz, telescopic coils or the like, converted intocorresponding alternating voltages which are in duplex connection andconducted to an amplifier 6 in known manner.

Methods and means for generating a measuring known to everybody who isskilled in the art.

These methods are based essentially on the principle to tap by means ofpotentiometers partial voltages of the voltages generated by thetransformers and to superimpose these partial voltages. Such anarrangement is explained in detail by way of example in the U. S. patentspecification No. 2,165,024.

Coupled to the body I is a rotary-field converter as will be hereinaftermore fully described. The stator of the latter, as clearly shown in Fig.3, has a rotary-field winding and a rotating armature 3 which throughthe poles i, l" is supplied with direct current. The points of thetriangle of the delta connection" of? the rotary-field winding areconnected to correspond-'- ing' points of a similar rotary-field system9 whose armature winding it is connected to poles 9', 9". A circularscale I! divided in minutes of angles is secured upon the shaft oftherotaryfield system 9 and cooperates with an indicator 52.

The rotor It is driven from an auxiliary motor [3 through a train ofreducing gears with built-in electromagnetic clutch I4.

As the armature 8 is rotated a rotating field is induced. in the statorsof the rotary-field systems i and 9. The latter in turn induces anauxiliary alternating current in the rotor it (which at first isto bethought of as standing still) the frequency of which conforms to therotary frequency of the rotor 8, respectively body I. this alternatingcurrent is continuously changed due to the low rotary speed of the rotoriii.

The alternating test current originating in the amplifier 8 is deliveredto the poles l5, l of a known modulator it, the: wiring diagram ofwhich.

is illustrated in Fig. 2. The auxiliary alternating The phase of 7 abovedescribed is the following:

current taken from the poles 9, 9', is likewise delivered to modulatorit through the poles ll, i1, and so, through a change-over switchgear,as will be hereinafter more fully described. A. DC. measuring.instrument is, is connected to thepoleslii, it of the modulator it. Theconnection of the valve modulator. it is known. Such a connection hasbeen represented in Fig. Zand merely is given asanexample. This con-.nection substantially comprisesthe following elements: The twomodulating tubes 36 and 31 each has one cathode 38,0r stand one anode18a and 5th, moreover each of the modulating tubes has two control grids!5d and Ila or 5513 and Mb. The reference characters 3611 and. 36b andalso tia and tlbdesignatescreen grids the task of which is merely toimprove the performance of the tube. Between the cathodes 38 or 39 andthe anodesisa or Heb a voltage. acts through protective resistors 32 andor M and 44. The test current across the poles i5, i5 is. connected inphase with the grids l5a and lib of the modulator tubes, whereas theauxiliary alternating current across the poles li, H is. connected outof phase with the second grids Ha, ill) of the modulator tubes.

In this circuit, as. isv known, a difference of potential is produced.across the anodes lea, l8bof the modulator tubes which is. dependentupon the phase relation of the two alternating voltages as to eachother. This, diiference of potential on the poles l8, l8 will be zero,

if. there is a 99 or 270 phase displacement of the auxiliary current onthe poles ll, H as compared with the alternating test current on'thepoles i5, i5. .However, if. thephase displace- The set by means of apotentiometer 29 in the modulator it.

The zero position of the pointer 2| is in the middle of the scale 22. Asthe pointer 2! is in zero position a relay 25 is actuated through aphoto-cell amplifierzt by known photo-electric cell controls 23. Therelay contact maker 28 then releases a switch member 2? which is underthe effect of a tension spring 28. A contact spring as connected withthe switch member 2'! is-also connected to the pole t. The contactspring as is in working contact either with the contact springic or 3!;The contact spring 39 is connected through an ohmic resistance 32 to themodulator pole i1, and similarly the contact spring 3i through acondenser 33. The magnetic clutch it and a signal lamp 36 can beconnected to the line voltage by means of another pair of contactsprings 3t, 35 which are actuated by the switch member 27. Onenergization of the clutch is the same will be released and the rotor isof the phase advancer 5 will be stopped. Q11 switching oif the switchmember 21 is returned and its. spring 28 is put in tension by a nose 3?of the main switch.

The principle of action of the. arrangement switch is switched on, thebody i to be balanced begins torotate. Thereby an alternating testcurrent is generated, on the one hand, on the poles i5, i5 and anauxiliary alternating current on the poles 9, 9, on the other hand, thephase of which is slowly continuously displaced by means. of the drivingmotor l3. Along with this the ohmic resistance 32 is connected throughthe contact spings 29, 33 to the circuit of the auxiliary alternatingcurrent. As soon as there is a phase displacement of or 270betweentesting current and auxiliary current the pointer 2i proceeds to zerowhereby the relay 25 is actuated and releases the contact maker 25. Bymeans of the release. of the switch member 21 contact is establishedfrom 3 to 35 whereby the clutch it is thrown out and the armature lilbrought to a standstill. signal lamp as comes on. The position of therotor is at the momentv of standstill is now'indicated on and can be.readfrom the scale I i and the'location of the unbalance thus be derivedtherefrom.

However, simultaneously with the release of the switch member 2.7contact between 29 and as is interrupted and in place thereof contactbetween 2t and 3! established. Instead of the ohmic resistance 32 thereis now the condenser 33 in the circuit of the auxiliary alternatingcurrent and effects 99 phase displacement. As a necessary result of. theabove there will be a deflection or the pointer 25 either to the left orto the right according as to whether the zero reading previouslyobtained was due to a phase displacement of 90 or to such a one of2'?0.'

pointed out, the teaching of the present invention is not confinedsolely to devices employing thede- As the main At the same time thescribed modulator connection and the described manner of phasedisplacement and change-over as these functions are obtainable also byother means. The described relay control is also not restricted tophoto-electric cell means but any known form of control device may beemployed.

What is claimed is:

1. Balancing machine for ascertaining the un balance of a revolving bodycomprising electromechanical transformers subjected to the forces ofunbalance generating an alternating current proportional to theunbalance, an alternating current generator rotating with said body andadapted for generating an auxiliary alternating current, an indicatingdevice supplied with said two alternating currents and indicating theproduct of said alternating currents with regard to their relative phasethere being electric circuits connecting said device with saidtransformers and generator, means for changing the phase of one of saidalternating currents continuously and measurably interposed in one ofthe alternating current circuits, an auxiliary drive for said phasechanging means including an electric energizing circuit, a controldevice cooperating with said indicating device, a relay actuated by saidcontrol device on zero indication of said indicating device, aswitchgear released by said relay, said switchgear interposed in thecircuit of said auxiliary drive and switching off said auxiliary drive,and means for a phase displacement of 90 connectable to one of saidalternating current circuits by said switchgear simultaneously with theswitching off action of said auxiliary drive.

2. Balancing machine for ascertaining the unbalance of a revolving bodycomprising electromechanical transformers subjected to the force ofunbalance generating an alternating current proportional to theunbalance, an alternating current generator rotating with said body andadapted for generating an alternating current, a modulator formultiplicatively compounding said alternating currents connects to thecircuits of said alternating currents, there being electric circuitsconnecting said modulator with said transformers and said generator, adirect current indicating instrument having its zero point in the middleof its scale connected to said modulator, means for changing the phaseof one of said alternating currents continuously and measurablyinterposed in one of the alternating current circuits, an auxiliarydrive for said phase changing means including an electric energizingcircuit,

a control device cooperating With said indicating device, a relayactuated by said control device on zero indication of said indicatingdevice, a switchgear released by said relay, said switchgear interposedin the circuit of said auxiliary drive and switching 011 said auxiliarydrive, and means for a phase displacement of connectable to one of saidalternating current circuits by said switchgear simultaneously with theswitching off action of said auxiliary drive.

3. Balancing machine for ascertaining the unbalance of a revolving bodycomprising electromechanical transformers subjected to the forces ofunbalance generating an alternating current proportional to theunbalance, a rotary-field system whose rotor is supplied with directcurrent and rotates with said body to be balanced, another rotary-fieldsystem electrically connected in parallel with said first rotary-fieldsystem and including another rotor, an auxiliary drive for the rotor ofsaid last named rotary-field system, an electro-magnetic clutch betweensaid auxiliary drive and said last named rotor and an energizing circuittherefor, an angle indicating device upon the shaft of said last namedrotor, said angle indicating device having a scale divided in minutes ofangle, an indicating device supplied on the one hand with saidalternating current which is proportional to the unbalance and on theother hand with the alternating armature current in the rotor of saidlast named rotary-field system there being electric circuits connectingsaid device with said transformers and said last named rotor, saidindicating device indicating the product of said alternating currentswith regard to their relative phase, a control device cooperating withsaid indicating device, a relay actuated by said control device on zeroindication of said indicating device, a switchgear in said energizingcircuit released by said relay and adapted to operate saidelectro-magnetic clutch, and means for causing a phase displacement of90 connectable to one of said alternating current circuits by saidswitchgear simultaneously with the operation of said clutch.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,118,770 Sivertsen May 24, 1938 2,362,842 Mueller Nov. 14,1944

